Re: [ATM] F/10 or F/8?

[Kevin Whitefire <chaosopher23@yahoo.com>]

Try for f/6, and use the 'scope with a Barlow of 2x,
2.5x, 3x, or whatever f/D works with a longer-focus
eyepiece.  I think Barlows are made up to 5x?  That
25mm eyepiece only gets about 50x with the 8" f/6, but
if you put that Barlow in place, you have 100x or
more, but the longer eye relief of the 25mm eyepiece. 
Personally, I don't like short-focus eyepieces.  The
tiny eye lens and my coordination don't mix.  Give me
a big pipe to look through any night.

That's one of the reasons I'm working on a cass of
f/22.

Kevin of Eastern Iowa (I wanna go home to RI )
Seeker of the Darkness

--- Curtis Spivey <curtis.spivey@gmail.com> wrote:

> Can anyone tell me if there would be any advantage
> in making a mirror
> in an F/10 vs. a F/8?  Seems like everything is a an
> F8.  This will be
> for a 6" mirror for primary use in a planetary
> scope.  My thinking is
> that with the longer focal length it will help with
> higher
> magnification for planetary viewing and may be a
> little more forgiving
> for a "first" mirror.  I also wear glasses and
> understand that you can
> use longer focus eyepieces with the longer F/R.
> Since this will be my first, I need all the help I
> can get.  Not, that
> I intend to do a poor job.  I just don't want to
> make this more
> difficult than it has to be.
> 
> 
> -- 
> Curtis
> Nampa, Idaho
> _______________________________________________
> ATM mailing list http://www.atmlist.net/
> 



		
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